For all the things Romans got wrong (lead pipes anyone?) did you know we’re still using a less advanced concrete than they did? Consider some of the massive structures in Rome that have passed the test of time, lasting for more than 2000 years. The typical concrete that we use in construction starts to degrade after only 50 years.
Researchers at Berkeley think they’ve finally figured it out with thanks to a sample that was removed from the Pozzuoli Bay near Naples, Italy. This could vastly improve the durability of modern concrete, and even reduce the carbon footprint from making it. The downside is a longer curing time, and resource allocation — it wouldn’t be possible to completely replace modern cement due to the limited supply of fly ash (an industrial waste product produced by burning coal). Their research can be found in a few articles, however they are both behind pay walls.
[misterdob] wanted to spice up his Halloween decor, so he built these flaming concrete jack -o’-lanterns to decorate his walkway. He started with the classic plastic jack-o’-lanterns that trick-or-treaters have been using to collect candy for years. [misterdob] filled the plastic pumpkins halfway with concrete mix, then dropped in metal coffee cans. He then filled the pumpkins up to the top with concrete, shaking them up a bit to avoid air pockets.
Once the concrete had set, [misterdob] cut away the plastic revealing nearly perfect concrete duplicates. He used acid stain to color his creations – though it looks like he missed a spot or two.
We have to disagree with [misterdob’s] choice of fuels. In fact, we think he was out of his gourd when he picked gasoline for his flaming pumpkins. Seriously though, gasoline is a horrible choice for a fire pot like this for a multitude of reasons. Gas has a particularly foul odor and its fumes are explosive. If a Halloween prankster were to try kicking one of the pumpkins over, not only would they have a broken foot, they’d also be covered in burning gas.
Thankfully, the folks on [misterdob’s] Reddit thread had better fuel suggestions – citronella torch cans with lamp oil and wicks, kerosene, or gel fuel would be better suited for these hot pumpkins.
After two years of dreaming, designing, and doing, [Andrey Rudenko] has finally finished 3D printing his concrete castle. We’re sure a few readers will race to the comments to criticize the use of “castle” as an acceptable descriptor, but they’d be missing the point. It’s been only three months since he was testing the thing out in his garage, and now there’s a beautiful, freestanding structure in his yard, custom-printed.
There are no action shots of the printer setup as it lays down fat beads of concrete, only close-ups of the nozzle, but the castle was printed on-site outdoors. It wasn’t, however, printed in one piece. [Andrey] churned out the turrets separately and attached them later. He won’t be doing that again, though, because moving them in place was quite the burden. On his webpage, [Andrey] shares some insight in a wrap-up of the construction process. After much experimentation, he settled on a layer height of 10mm with a 30mm width for best results. He also discovered that he could print much more than his original estimation of 50cm of vertical height a day (fearing the lower layers would buckle).
With the castle a success, [Andrey] plans to expand his website to include a “posting wall for new ideas and findings.” We’re not sure whether that statement suggests that he would provide open-source access to everything or just feature updates of his future projects.
We hope the former. You can check out its current format as the Architecture Forum, where he explains some of the construction capabilities and tricks used to build the castle.
His next project, a full-scale livable structure, will attempt to print 24/7 (weather permitting) rather than the stop-start routine used for the castle, which turned out to be the culprit behind imperfections in the print. He’ll have to hurry, though. [Andrey] lives in Minnesota, and the climate will soon cause construction to take a 6-month hiatus until warm weather returns. Be sure to check out his website for more photos and a retrospective on the castle project, as well as contact information—[Andrey] is reaching out to interested parties with the appropriate skills (and investors) who may want to help with the new project.
We don’t see many behind the scenes industrial-scale projects here at Hackaday, but we’re definitely impressed with the clever techniques employed to pull off this precision install. At around 5 inches deep, the original floor was far too thin to handle the weight and tortional loads imposed by Project Jeff, so The Geek Group carved out a 15′ square space of old concrete and dumped it piece by piece in the rubbish. They then dug a new hole to a depth of 2.5′ and filled it with a fresh pour that amounted to 67,500 pounds of concrete. Sheesh.
That concrete will inevitably expand and move around, which meant installing a pool-noodle-looking slip cover to protect a buried conduit from damage, as well as placing some gaskets around the edges to prevent cracking while maintaining a seal. Around 10 minutes into the video, they tackle the challenge of embedding bolts that connect to the robot’s base; it takes some patience and creative ladder positioning to fit the template in the correct position.
As an added treat, The Geek Group smashed a CRT monitor in our honor, and while they claim software limitations and a steel frame prevented Project Jeff from completely annihilating the monitor, we like to think the skull and cross-wrenches just refused to be destroyed. Because, you know, science. Videos after the break.
Members of the Warp Zone hackerspace wanted a coffee table that was beyond ordinary. They ended up pouring a concrete base for the glass top (translated). There were several things to address during the design. First off, they wanted to integrate LEDs in the concrete sides. Some consideration had to be made for portability as concrete is very heavy. The final piece of the puzzle was deciding what kind of hardware to place beneath the frosted glass.
The legs were designed with a large cut-out area to keep them as light weight as possible. The cross piece has a set of voids spelling out the name of the hackerspace with some green LEDs. This was accomplished by placing foam cut-outs of each letter in the forms before for concrete was poured. They sealed around each letter with silicone, but still had some seepage most likely caused when jostling the form to help remove air bubbles. Straws were placed in the foam to allow a cable pass through for the electronics. After everything was in place they filled the voids with hot glue to act as a diffuser.
There aren’t a lot of details about the RGB LEDs under the frosted glass. But you can see the light show they produce in the clip after the break.
At the 2009 Ghana Maker Faire, [Pat Delany] met a young carpentry student that saved for three months to buy a cheap Chinese wood plane. He was confounded by this distribution of resources, so [Pat] created the Concrete Lathe project that aims to get useful machine tools out to where they’re needed most.
The idea for concrete machine tools came out of the US involvement in World War I. America had been staunchly isolationist before committing to the war, and production of arms did not match the needed output. A man named L.I. Yeomans came up with the idea of building concrete lathes to produce artillery shells for the war effort.
Of course, the concrete lathe project is a bit more peaceful in its intentions. The concrete lathe is meant to be a cheap machine tool for developing nations. Both the concrete lathe and the Multimachine are meant to be built cheaply using scrap materials, reduce training time for machinists, and create other machine tools in a Reprap-like biological distribution.
These speakers are hand made and almost one of a kind. [Lluís Pujolàs] didn’t come up with the original design, but he sure did an amazing job of crafting them, including an eleven page build log (translated). They’re called the Odyssey 2, after the original design. The shell-shaped cavity on the bottom was built as a wooden skeleton first, then covered over for the finished shape. But the mid and high range enclosures were turned on a lathe from wood glued-ups. A serious machine shop is necessary to do this kind of woodworking. The bases are poured concrete, impregnated with lead beads to help with vibration isolation. At 330 pounds each it’s understandable that he tested them on wheels before parking them in their final position as seen above.